Heat exchange conduit with a spiral fin having a capillary groove



Jan. 13, 1948. w. RASKIN 2,434,519

HEAT EXCHANGE CONDUIT WITH A SPIRAL FIN HAVING A CAPILLARY GROOVE Filed April 18, 1942 INVENTOR. VWJL TEe PAS/(ml BY J/Z Q A T TOR/V673 frigerating Patented Jan. 13, 1948 2,434,519 HEAT EXCHANGE CONDUIT WITH A SPIRAL FIN HAVING A CAPILLARY GROOVE Walter Raskin, New York, N. Y. Application April 18, 1942, Serial No. 439,471 1 Claim. (01. 257-262) This invention relates to a heat exchange device or heat absorption device and to a refrigerant tube used equipment. 4

One of the principal objects of the invention is to increase the heat exchange surface or' the evaporator surface to a maximum.

Another object is to utilize the capillary attraction principle in moistening the evaporator surfaces with the refrigerant.

Still a further object is to increase the turbulence of the refrigerant through the evaporator conduit without loss of energy and without appreciable friction increase.

Still a further object is to provide a heat exchange device or an evaporator conduit with added primary heat exchange or evaporator surfaces.

Other objects and advantages inherent in the invention will become apparent from the following description taken in conjunction with the attached drawing which illustrates, by way of example, various embodiments of the invention.

In the drawing:

Figure 1 is a perspective view of one embodiment of the invention; a

Figure 2 is a fragmentary top plan view of the device shown in Figure l drawn to a somewhat enlarged scale;

Figure 3 is a bodiment;

Figure 4 is a front elevation of a modification;

Figure 5 is a section taken along the line 5-5 of Figure 4;

Figure 6 is a cross-section of another modification; and,

Figure 7 is a cross-sectional view of still another modification.

Throughout the drawing the same reference characters are used to designate the same or analogous parts.

Referring in greater detail to the drawing, the device comprises. a closed tubular portion l0 formed of sheet metal or similar material.

In the modification shown in Figure l, the ends of the sheet defining the tubular portion are bent and pinched together and welded to form a flange or fin l2. The ends are bent outwardly again perspective view of another emin opposite directions to provide lateral extensions, as shown in Figure 1. These lateral extensions are preferably slit to form a series of blades i3 which are turned or twisted in the manner of air foil sections. This arrangement produces turbulence of the air passing over the blades and thus it is brought into more intimate contact with the evaporator surfaces.

In the embodiments shown in Figure 3, the wall of the tubular portion is extruded to form a plurality of fins M. The walls of the fins are spaced to define an intermediate slot l5 which opens into the tube. Thus the fins l4 become part of the primary evaporator surface when the tube is flooded with the refrigerating medium.

However, if the width of the slots I5 is too large, little or no refrigerant will penetrate into the fin, except by forced fiow. Such forced flow will cause a friction drop and require considerably more energy and will thus increase the load upon the operating machinery and decrease the emciency of the device generally.

This objection has been overcome by the invention by making the width of the flow of such dimension that the refrigerant will penetrate into the slot through capillary attraction. It will be understood that a mere wetting or moistening of the interior surfaces of the slot will suffice to cause heat absorption.

In the modification illustrated in Figure 4, the turbulence of the refrigerant is increased by arranging the fins "5 in a spiral or helical fashion about the evaporator tube Ill. The fin I6 is provided with a slot I! in a manner similar to the embodiment shown in Figure 3. The spiral periphery has a relatively great pitch. In addition to the increased turbulence resulting from this construction, which feature is a very important factor in refrigerating equipment, the spiral will also have the effect of a sharply inclined plane of great mechanical advantage. By virtue of this construction, the refrigerant will be brought to the top of the slot and complete wetting of the inner surfaces of the tube as well as of the fins will be assured. This will prevent partial starvation of the tube as well as of the fins.

It will be understood that the invention is not limited to any particular number of fins. The evaporator tube, according to the invention, may have two fins, as shown in Figures 4 and 5, or as shown in the modification illustrated in Figure 7,

or it may have four fins, as shown in Figure 6, or

a greater number, as demonstrated in Figure 3.

It will also be understoodthat the foregoing description is given by way of example only and not byway of limitation. The invention may find expression in a great variety of other modifications within the scope of the following claim.

What is claimed is:

A heat exchange device comprising a tubular portion, a fin portion extending spirally about said tubular portion, said fin portion having a longitudinal slot opening along said conduit, whereby said fin portion will become part of the primary evaporator surface, the width of said slot being of such dimension that capillary attraction will 5 cause the refrigerant to penetrate into said slot. WALTER RASKIN.

REFERENCES CITED The following references are of record in the 10 file of this patent:

Number UNITED STATES PATENTS Name Date Murray June 4, 1929 Morrison Aug. 30, 1932 Heitman Apr. 9, 1935 Higham et a1 June 13, 1939 Gould May 6, 1941 Schoen Apr. 28, 1942 Brown June 23, 1942 

